The present invention relates generally to fluid filtering apparatus which are arranged to be cleaned by a reversed backwashing flow.
Heretofore, it has been generally known to provide filtering apparatus in which the filter unit is arranged to be connected for normal filtering flow of the fluid to be filtered in one direction through the filter, and periodically reverse the direction of flow through the filter to remove the accumulated filtered out media. In many installations, the reverse flow or backwashing procedure, as previously practiced, is not entirely satisfactory for the reason that much of the filtered out media becomes lodged in the filter and is not effectively removed by the usual reverse flow or backwashing process.
In the development of the filter apparatus of the present invention it was found that the backwashing procedure could be greatly improved by providing some means by which the backwashing flow could be initiated with an explosive-like surge which could be relied upon to effectively loosen and remove the embedded filtered out media. Moreover, further investigation indicated that such an explosive-like surge could be obtained by the utilization of a backwashing valve of large capacity which could be quickly opened by an inertial or other type of operator which could quickly move the valve to a full open position.
While the prior art discloses valve structures generally which utilize an impacting member for applying an impact force to open the valve, or arrangements which utilize pneumatic and hydraulic actuators, the prior art patents have not envisioned the concept of using the quick-acting valve in a filter backwashing arrangement.
The Hansen et al U.S. Pat. No. 1,596,968, issued Aug. 24, 1926 discloses a magnetically operated valve wherein a magnet is energized to actuate a toggle linkage which causes downward movement of a hammer in order to impart an impact force to a spring-loaded, normally closed valve.
The Tratsch U.S. Pat. No. 1,854,605, issued Apr. 19, 1932 discloses an air gun in which a hammer head is moved to compress a spring by pulling of a trigger rearwardly, and upon release of the hammer to forcibly strike the stem of the air valve so as to momentarily unseat the valve and permit a flow of pressurized air to propel the projectile.
It has also been known from the Allen U.S. Pat. No. 3,770,241, issued Nov. 6, 1973 to provide a hand actuated springbiased impacting member arranged for imparting motion to a transfer member, and subsequently to a one-way clutch means which rotates a closure member or valve element.
Pneumatic and hydraulic valve opeators are known generally, and as indicated by the Knight U.S. Pat. No. 3,884,251, issued May 20, 1975, it has been previously known to utilize a valve having a valve stem telescopically connected to a pneumatic or hydraulic power actuator.
The prior art disclosures as noted above are lacking in the essential features which are incorporated in the unique filtering apparatus and backwash valve of the present invention to produce a quick opening valve action which will result in the production of an explosive-like surge upon the initiation of the backwashing flow, and which will effectively dislodge the embedded filtered out media.